Vaccine could protect against cancer caused by organ transplants

People who have received organ transplants are 250 times more likely to develop non-melanoma skin cancer than the normal population. The exact cause of this cancer is not known for sure but scientists say it is highlylikely to be thehuman papillomavirus(HPV). New research using anuncommon African mousesuggeststhese suspicions are well-founded, and that a vaccine could be used to protect transplant patients when theyare at their most vulnerable.

HPVinfects the skin and is spread through close skin-to-skin contact. Infection is very common but usuallycauses no symptoms at all; up to 8 out of 10 people will be infected with the virus at some point in their lives,many without knowing. However,donor organ recipientsmust take drugs that suppress their immune systemto avoid organ rejection. This can leave them open to serious infection by HPV, which causes painful skinlesions that can persist for many years. And in some cases these can turn cancerous.

To study HPV infection, researchers turned to an unusual and not often used lab mouse, the Africanmultimammate mouse (Mastomys coucha). Like humans, this species of mouse is naturally infected withpapillomaviruses during early life and can later go on to develop symptoms such as warts and benigntumours in the skin.

The researchers produced experimental vaccines using virus-like particles, which are essentially empty viralshells without any infectious DNA. HPV vaccines already on market and routinely given to schoolgirls toprotect against cervical cancer are also produced using this method.

When these vaccines were given to the mice, none went on to developsymptoms of infection or skin cancer. Crucially for transplant patients, theprotective effect was still seen when the mice were givenimmunosuppressive drugs. This suggests that a vaccine administeredbefore surgery could reduce or prevent the risk of HPV infection and thedevelopment of cancer in the recovering patient. More research will beneeded, including clinical trials, to find out whether this is true.

This is thefirst time the African mousehas been used in HPV vaccine research and development. Vaccinesalready available for other HPV-linked cancers were developed primarily using cows, dogs and rabbits. Themouse could prove highly useful in future research and may even reduce the need for research on these other species.